Folate-Functionalized Amphiphilic Chitosan Polymeric Micelles Containing Andrographolide Analogue (3A.1) for Colorectal Cancer

Abstract

A site-specific drug delivery system of anticancer agents has been delveloped to enhance the therapeutic efficacy and reduce toxicity to the normal tissue. Semi-synthetic andrographolide analogue 3A.1 (19-tert-butyldiphenylsilyl-8,17-epoxy andrographolide) is one of the potential natural anticancer compounds against many types of cancer including colorectal cancer cells. However, the clinical applications of this compound are limited because of low water solubility and lack of suitable delivery carriers. This study aimed to increase the aqueous solubility and improve the anticancer efficacy of 3A.1 via active targeting approaches. In this study, 3A.1 was loaded into the polymeric micelles self-assembled from N-naphthyl-N,O-succinyl chitosan (NSC). The micelles were conjugated with folate moiety (Fol-NSC) for targeting to the cancer cells. All of the 3A.1-loaded micelles were prepared by dropping method, and the physicochemical properties (size, charge, morphology, encapsulating efficiency, loading capacity), in vitro release behavior and in vitro anticancer activities against HT29 colorectal cancer cells were investigated. The 3A.1-loaded micelles were successfully formulated by dropping method using NSC or Fol-NSC. The micelles loaded with 40% initial 3A.1 showed the maximum encapsulating efficiency and loading capacity. The micelles were in the nanometer range, having a negative surface charge and a spherical structure. The colon site-specific release of the 3A.1 from the 3A.1-loaded micelles was obtained. The release of 3A.1 from the Fol-NSC micelles was slower than that from the NSC micelles. Moreover, the Fol-NSC micelles exhibited superior anticancer efficacy than that of the NSC micelles and free 3A.1. In conclusions, the 3A.1-loaded Fol-NSC micelles developed in the present study had suitable physicochemical properties. These nanocarriers may be a potential delivery system for targeted delivery of the 3A.1 to colorectal cancer cells.